Electric shaver control assembly



Sept 13, w66 M, M. A.TROU1LHET 3,272,943

ELECTRIC SHAVER CONTROL ASSEMBLY 2 Sheets-Sheet l Filed April 16, 1964 o w Mv r /n M 0 .L O I Lmwv www .Wn A VMT n e Ie# .mM rc MA W M Sep@- S, i966 M. M. A. 'moulu-:ET 3,272,943

ELECTRIC SHAVER CONTROL ASSEMBLY Filed April 16, 1964 2 Sheets-Sheet 2 United States Patent O "ice s Claims. (ci. 20o- 122) The present invention relates principally to an overheat protection device for electric circuits. This device is of the ltype having -a bimetallic strip connected as a circuit breaker to the electrical circuits of various installations, and particularly of electromagnetic units.

Practically, numerous protector devices have already been proposed, especially of the type using a bimetallic strip, undergoing a deformation which is a function of its temperature, i.e. usually Ia -function of the ambient temperature. Such device has the `disadvantage of lacking accuracy, since it=s actuation is related to the ambient temperature, that is to a phenomenon which is largely irrelevant to the heating of the units to be protected. Moreover, especially in the protection of a motor subjected to a substantial transient overcurrent, i.e. to a momentary overor under-voltage, the motor coil may be completely damaged before the strip motor has sufficiently heated the bimetallic strip to actuate the safety device.

Of course, use may be made of the Well-known protector using a fuse Wire connected in series in the circuit supplying power to the apparatus to be protected. This type of protection, besides constraining the user to replace the fuse wire each time the latter fuses, is unfortunately without effect in the case of a moderate, but prolonged overcurrent (resulting for example of a corresponding overor under-voltage), which however imposes on the electrical units used under such conditions an abnormal heating liable to impair them by duration effect. In particular, the rotary electric motors and electromagnetic vibrators are highly sensitive to said effect.

The present invention provides in combination reliable cut-off in case of a high overcurrent, such -as is generally afforded by a fuse wire, and reliable actuation of a bimetallic strip in case of a moderate, but prolonged overcurrent. However, it is attended by none of the inconveniences inherent to the aforesaid devices, viz. on the one hand, the necessity to replace the fuse Wire and, on the other hand, the lack of accuracy of the usual bimetallic element which is ydependent upon the ambient ternpera-ture.

According to one characteristic of the protector device in accordance with the invention, said device includes at least one bimetallic strip, the position of which determines the opening or closing of the electric -circuit to be controlled, and a heating resistance wire mounted adjacent to said bimetal and connected in series or in parallel with the electric circuit under control.

According to another characteristic of the invention, said heating resistance wire is helically wound around said bimetallic strip.

It will then be understood that with this arrangement since the current flowing through the heating resistance Wire around the bimetallic strip is either equal or proportional to the current flowing through the electric circuit 3,272,943 Patented Sept. 13, 1966l to be controlled, the bimetallic strip will heat up according to a law quite similar to that governing the units connected to the electric circuit under control, i.e. according to the square of the current flowing therethrough.

In this manner, any abrupt overcurrent Will result in a quick heating of the resistance wire, i.e. a heating at least as rapid as that of the electric units connected in the circuit under control. This substantially instantaneous heating will cause a deformation of the bimetallic strip and thus the opening of the electric circuit to protect the units connected thereto.

On Ithe contrary, upon any low, but prolonged overcurrent, e.g. `due to a slight overvoltage in the mains, the heating up of the resistance Wire will -actuate the bimetallic strip after a period of such duration that the heating of the electric units connected to the controlled circuit would otherwise become prohibitive.

Of course, after a time interval sufficient for the heat-4 ing resistance wire and bimetallic strip t-o cool down, said strip will move back to its initial closed position, thereby allowing for further operation of the thus reset electric circuit.

According to another characteristic of the invention, a sleeve is provided to afford electrical insulation between the aforesaid strip and resistance wire.

Moreover, the invention encompasses, as new products of manufacture, the electric units and systems using the present protector device, and especially electromagnetic units such as electric razors and clippers thus protected.

Further characteristics of the invention will appear as the following description proceeds.

In the attached dra-wings, given by mere way of example:

FIGURE l is a sectional view of a device according to the invention, taken along line I-I of FIGURE 2.

FIGURE 2 is a view from above of the device showny in FIGURE l.

FIGURES 3 and 4 are two sectional views, taken along lines III-III of FIGURE 4 and IV-IV of FIGURE 3 respectively, illustrating an application of a protector device similar to that shown in FIGURES 1 and 2, for example to a two voltage electric razor.

FIGURE 5 shows the voltage changer of the apparatus shown in FIGURES 3 and 4 in a different position from that shown in FIGURE 3.

According to the embodiment of FIGURES 1 and 2, a protector device in accordance with the invention comprises principally a bimetallic strip or bimetal 1 which is secured to an insulating support 2, e.g. of card- Iboard coated with Bakelite, by means of a rivet 3. Secured to the free end 1a of t-he bimetal 11 is an insulating part 4, which may be iitted onto the bimetal. A contact '5 is provided on the insulating part 4. -Fast With the insulating support 2 is a metal part 6 which carries a contact 7 opposite to contact 5 carried by the bimetal and which may for example be riveted -to support 2.

An insulating sleeve or bushing 8 is mounted on the bimetal and may be mad-e of a moulded insulating material having good resistance to temperature rises, such as polytetrauorethylene.

In FIGURES l and 2, there is diagrammatically shown at 9 a standard current-.supply plug an-d at 10 and 1v1 the respective inlet and outlet wires for the current flowing through the protector device 12 such as hereinabove described, whereas a working unit is shown in blockform at 13.

Considering FIGURES l and 2, it will be seen that the electric current flows successively through: the current-supply wire 10; resistance wire 14 which is secured, for example, by welding, at a point 15 of the bimetal '1, then wound around the insulating sleeve 8 and secured by its other end to contact c-ontacts 5 and 7, when the latter are pressed against each other by the sufficiently cold bimetal 1; conducting part 6; wire 10', which is fastened to part 6, for example by means of a contactrivet 17; unit 13; then outlet wire 11.

. The operation of the device will easily be deduced from the above description. When plug 9 is connected, e.g. to the mains, bimetal -1 being cold, contacts 5 and 7 .are pressed `against each other. Under these conditi-ons, and uni-t 13. As long as unit 13 is operating normally, the electric current ows in series through the device 12 i.e. not subjected to any overcurrent, the resistance wire 14 is not suiciently heated to raise the bimetalto a temperature at which the latter will warp and thereby open contacts 5 and 7. The supply to unit 13 will therefore be continued.

lOn the contrary, upon any overcurrent, either of great magnitude and indeterminate duration or of low magnitude land long duration, then the resistance wire 14 becomes sufficiently heated for the bimetal to distort and separate contacts 5 and 7, unit 13 being thus cutout.

If desired, apertures or perforations may be provided in sleeve 8 to promote the iiow of heat from the resistance wire .14 to the bimetal.

'In FIGURES 1 and 2, it will be noticed that the resistance wire 14 is in series with unit 13 which is to be protected by device 12, w-hile no current flows through bimetal 1 itself. If so desired, the resistance wire 14 may be shunted lacross the supply-wire of unit 13, provided that the contacts 5, 7 remain connected in series to the Isupply circuit of unit 13. The opera-tion of the operator of the protector device shown in FIGURES 1 and 2 remains then quite unchanged.

FIGURES 3 and 4 more precisely illustrate the application of a protector device similar to that shown inthe preceding iigures, to a vibrator, e.g. for an electric razor, including two inductor coils 18 and 1-9. In FIGURES 3 and 4, the same references as in FIGURES 1 and 2 are used to denote similar parts.

Thus, there Will be seen in these figures a bimetal 1, surrounded by its heating resistance wire 14, which is connected in ser-ies to the supply circuit |10, 11 of the vibrator. The bimetal 1 is mounted on its insulating support 2 and the mounting of contact 5 at the free end of the bimetal is the lsame as in FIGURES 1 and 2. In the embodiment illustrated by FIGURES 3 and 4, the insulating plate 2 is secured to the razor case 20, e.g. by means of four stu-ds 21 moulded integral with case 20; the plugs 10 and 11 supplying current to the razor are of the type usual in such units and are to be used with a ,special line-cord for the razor. Said plugs 10` and 1'1 are respectively connected to conducting part 6 carrying the lixed contact 7 and to plate 22, itself connected to one end of coil .19 through a contact-piece 23 and possibly, according to the position of the voltage switchbutton 26, to one end of coil 18, through a at contact rbar 24 and a conducting sector 25 of the voltage switchbutton 26 (when in its position shown in FIGURE B). When contacts 5, 7 are close-d, plug 10 is connected to wire l14 and therethrough to bimetal 1 at the welding spot 15. Bimetal 1, and therefore wire 14, are connected by a wire 27 to the other end of coil 18 and sometimes, according as the position of switch-button 26 such as shown in FIGURE 3, to the other end of coil 19, through sector 28, contact-bar 29 and wire 30. It will immediately be seen that, with the .arrangement of FIGURE 3, the inductor coils 18 and 19 of the electric razor are fed in parallel as long as contacts 5 and 7 remain closed. When due to any overcurrent, contacts 5, 7 are opened by the bimetal, then the supply to both coils 18 and 19 is cutoff.

When the switch-button is located as shown in FIG- URE 4, then the supply current will flow successively through plug l10, wire 14, wire 27, coil 18, contact-bar 24, contact-bar 29, wire 30, coil 19, plate 22 and the outlet plug 11, thus feeding in series the coils 18 and 19 of the razor. yIn this case also, .the opening of contacts `5, 7 will cut out both razor coils 18 and 19.

It will be understood that the invention Iis in no way limited to the embodiment described and shown, which is given by mere way of example.

What I clai-m is:

1. A control assembly for a shaver comprising a casing and an electric motor having two identical windings, said control assembly including an electric insulating plate secured to and spaced `from one wall of said casing, a first, a second, a third and a fourth electrically conductive strip-like members, secured to the face of said plate facing said casing wall, said members having respective free ends disposed at angularly spaced consecutive locations on a common imaginary circle parallel to said casing wall, said first and second members being respectively connectable to the terminals of a source of electric current, said lirst member being formed by a bimetal strip carrying at its end opposite to said free end a movable contact engageable with a fixed contact carried by a metal part secured to said insulating plate, said motor windings being respectively connected between said first and said third members and between said second and said fourth members, a voltage-switch button mounted in a hole formed in said casing wall coaxially with said imaginary circle and angularly movable between a tirst and a second position, the inner face of said button being provided with two sectoral contacts, said sectoral contacts respectively connecting said first to said fourth member and said second to said third member when said button is in said lirst position and one of said sectoral contacts connecting said third to said fourth member when said button is in said second position.

2. A control assembly for an electric shaver as set forth in clairn 1 wherein said movable contact is electrically insulated from said bimetal strip by an insulating part made of a synthetic resinous material force-fitted at the end of said bimetal strip opposite to said free end, said bimetal strip being surrounded by a yrigid and integral electric insulating sleeve made of a synthetic resinous material, slipped onto said bimetal strip and extending in the'longitudinal direction thereof, a heating resistance wire being helically wound around said sleeve for heating said bimetal strip, said sleeve being provided with heat-transfer apertures, said wire having its rst end electrically connected to said movable electric contact and its second end connected to said bimetal strip.

Y3. A control assembly for :an electrical shaver as set -forth in claim 2 wherein said bimetal strip and said metal part carrying ysaid iixed electric contact are secured on said insulating plate by means of a rivet.

4. A control assembly for an electric shaver as set forth in claim 3 wherein said movable electric contact is constituted of a rivet passing through said insulating part force-fitted onrsaid bimetal strip.

5. A control assembly for an electric shaver as set forth in cl-aim 4 wherein said resistance wire is secured by welding to said bimetal strip.

6. A control assembly for an electric shaver as set forth in claim 5 wherein said insulating material constituting said sleeve is constituted by polytetrafluorethylene.

7. A control assembly for an electric shaver as set forth in claim 6 wherein said electrical insulating sleeve is shaped in the form of a substantially parallelepipedic block provided with a longitudinal ypassage having a flat cross section.

8. A control assembly for an electric shaver as set forth in claim 1 wherein a hole is provided in said shaver 5 6 casing, an insulating insert being fitted within said hole 12,408,568 9/ 1946 McClure ZOO-122 `and supporting two current-supply spins extending through 3,003,086 10/ 1961 Strobel et al 200-122 X said insulating insert and respectively connected to said 3,023,350 2/ 1962 Broadley et al. 20G-122 metal part carrying a fixed contact and to said fourth FOREIGN PATENTS strip-like member.

679,475 9/1952 Great Britain.

References Cited by the Examiner '721,435 l/ 1955 Great Britain.

UNITED STATES PATENTS BERNARD A. G1LHEANY,Primary Examiner. 1,908,676 5/1933 Appelberg 219-511 2,302,924 11/1942 Valverde n 200 122 10 L. A. WRIGHT, AssistantExdmi/zer. 

1. A CONTROL ASSEMBLY FOR A SHAVER COMPRISING A CASING AND AN ELECTRIC MOTOR HAVING TWO IDENTICAL WINDINGS, SAID CONTROL ASSEMBLY INCLUDING AN ELECTRIC INSULATING PLATE SECURED TO AND SPACED FROM ONE WALL OF SAID CASING, A FIRST, A SECOND, A THIRD AND A FOURTH ELECTRICALLY CONDUCTIVE STRIP-LIKE MEMBERS, SECURED TO THE FACE OF SAID PLATE FACING SAID CASING WALL, SAID MEMBERS HAVING RESPECTIVE FREE ENDS DISPOSED AT ANGULARLY SPACED CONSECUTIVE LOCATIONS ON A COMMON IMAGINARY CIRCLE PARALLEL TO SAID CASING WALL, SAID FIRST AND SECOND MEMBERS BEING RESPECTIVELY CONNECTABLE TO THE TERMINALS OF A SOURCE OF ELECTRIC CURRENT, SAID FIRST MEMBER BEING FORMED BY A BIMETAL STRIP CARRYING AT ITS END OPPOSITE TO SAID FREE END A MOVABLE CONTACT ENGAGEABLE WITH A FIXED CONTACT CARRIED BY A METAL PART SECURED TO SAID INSULATING PLATE, SAID MOTOR WINDINGS BEING RESPECTIVELY CONNECTED BETWEEN SAID FIRST AND SAID THIRD MEMBERS AND BETWEEN SAID SECOND AND SAID FOURTH MEMBERS, A VOLTAGE-SWITCH BUTTON MOUNTED IN A HOLE FORMED IN SAID CASING WALL COAXIALLY WITH SAID IMAGINARY CIRCLE AND ANGULARLY MOVABLE BETWEEN A FIRST AND A SECOND POSITION, THE INNER FACE OF SAID BUTTON BEING PROVIDED WITH TWO SECTORAL CONTACTS, SAID SECTORAL CONTACTS RESPECTIVELY CONNECTING SAID FIRST TO SAID FOURTH MEMBER AND SAID SECOND TO SAID THIRD MEMBER WHEN SAID BUTON IS IN SAID FIRST POSITION AND ONE OF SAID SECTORAL CONTACTS CONNECTING SAID THIRD TO SAID FOURTH MEMBER WHEN SAID BUTTON IS IN SAID SECOND POSITION. 